Patent Document 1 discloses a production process of a complex semiconductor device. Specifically in this production process, after an InGaP layer is formed on a GaAs wafer as an etching stop layer, an AlAs layer is formed as a removal layer. Thereafter, a GaAs crystal layer is formed. Subsequently, a groove is formed to the wafer by lithography, from the surface of the wafer to the removal layer. Then using thus formed groove, an etchant is made to be in contact with the AlAs removal layer, to remove the AlAs removal layer, thereby removing the GaAs crystal layer from the GaAs wafer to produce an independent GaAs crystallization (LED epifilm). Next, the independent GaAs crystallization is attached to a silicon wafer, and wiring or the like is formed on the GaAs crystallization, to produce an LED array. Note that a removal layer is also called a sacrificial layer.    Patent Document 1: JP2004-207323 A